An 11-year-old boy and his parents have died after falling into a volcanic crater near Naples.

Italian press reports said the boy walked into a prohibited area at Solfatara di Pozzuoli, one of 40 volcanoes in the Campi Flegrei area west of Naples.

He is believed to have fainted due to gas fumes before falling into the crater. The boy’s parents tried to save him, but the crater collapsed.

Their other child, aged seven, survived because he had left the scene in search of help. The incident took place at about 11am on Tuesday.

The family, originally from Turin but living near Venice, were on a visit to the tourist site. Their bodies were recovered from the three-metre (10ft) crater by firefighters.

“Either there was a small explosion, or the ground simply gave way from their weight, and they fell into this hole,” national fire brigade spokesman Luca Cari said. Firefighters said they appeared to have died from asphyxia, possibly because of hot gases emanating from the ground.

The younger boy ran into a bar at the entrance of the crater, where he was comforted by staff for several hours.

Armando Guerriero, the bar’s owner, said: “He saw his parents and brother falling into the crater.

“He didn’t know whether they were alive or dead. He was crying and calling his mother’s name. In the 40 years that I’ve worked here, I’ve never seen anything like it.”

The dormant Solfatara, which last erupted in 1198, has a shallow crater and emits steam with sulphurous fumes. It is located in the Campi Flegrei, a sprawling constellation of ancient volcanic craters scorching hot just below the surface.

The volcano is managed by a private company and open all year round to visitors, who can go on a guided tour or explore it by themselves.